1. "Ligar depois" - This is the most common way to say "will call" and means "to call later." It's suitable for saying you'll call someone back.
2. "Vou telefonar" - This means "I will call" and is used when you are the one who will be making the call.
3. "Irá telefonar" - This means "He/She/It will call" and is used when someone else will be making the call.
4. "Vai telefonar" - This means "He/She/It will call" and is a more informal way to say it.
5. "Vai ligar" - This means "He/She/It will call" and is another informal option.
6. "Vai chamar" - This means "He/She/It will call" and is a more formal option.
Example:
* "Vou ligar para você mais tarde." (I will call you later.)
* "Ele vai telefonar para você amanhã." (He will call you tomorrow.)
* "Vou chamar um táxi." (I will call a taxi.)
The best option will depend on the specific context of your sentence.